Peskov added that he was accompanying Russian President Vladimir Putin to the meeting with the Vietnamese president, so he could not say if any document had been received by the Kremlin or not.

The Kremlin spokesman also declined to say what specific measures Russia could take to respond to sanctions. "There are various possibilities, it will depend on the government’s proposals. Since proposals come from the government, it is the government that should be asked to comment on them," he added.

Earlier on Wednesday, Russian Prime Minister Dmitry Medvedev said at a cabinet meeting that the government would submit to the president a proposal to extend retaliatory sanctions for one year, until December 31, 2018.

The prime minister pointed out that the European Union had already extended sanctions against Russia. According to Medvedev, he had discussed the extension of Russian sanctions with Putin.